President Obama said measures would "increase Russia's political isolation ". Credit: PA

President Barack Obama said the United States will join the European Union in imposing tougher sanctions on Russia's financial, energy and defence sectors after Moscow sent troops into eastern Ukraine last month.

"These measures will increase Russia's political isolation as well as the economic costs to Russia, especially in areas of importance to President Putin and those close to him," Obama said in a statement.

The President said the US will provide details on the new steps tomorrow.

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Pro-Kiev authorities in Mariupol, a frontline city in the conflict between Ukraine and pro-Russian separatists, have announced a night curfew and other restrictions for nearby towns and villages to help control rebel movements during a fragile ceasefire.

Ukrainian President Petro Poroshenko meets with Ukrainian servicemen during a visit to Mariupol earlier this week. Credit: Reuters

Some locals complained that the measures - which do not apply to the city of Mariupol itself - amounted to "undeclared martial law".

Others, however, said they were a necessary step enabling Ukrainian authorities to better monitor the shaky five-day ceasefire and prevent rebels exploiting it.

One military officer told Reuters: "This is not martial law. We want them to show themselves. If someone is out there between 8pm and 6am we will know they are not civilians and we can take appropriate measures."

Russia has carried out a successful test of its new Bulava intercontinental nuclear missile and will perform two more test launches in October and November, the head of its naval forces said.

The 12-metre long Bulava, or mace, has undergone numerous tests, some of which have failed, causing setbacks for the project that aims to be the cornerstone of Russia's nuclear arsenal over the next decade.

Drones will be deployed to monitor the ceasefire in Ukraine. The chairman of the Organisation for Security and Cooperation in Europe (OSCE), Didier Burkhalter, said their drones will be sent into the field soon.

He added the organisation is also holding talks on the possibility of using national drones as soon as possible as "in-kind contribution by participating states" in the monitoring scheme.